Device for loading film on machines for wrapping products

ABSTRACT

In a device for loading film ( 3 ) on machines for wrapping products, a carriage ( 4 ) which supports and moves a reel ( 5 ) has a guard ( 9 ) covering the end of a pair of rollers ( 6, 7 ) for pre-stretching and feeding the film ( 3 ), opposite the end attached to a platform ( 8 ) which supports the rollers; the guard ( 9 ) covers each roller ( 6, 7 ) in such a way that it defines a continuous through-channel (C) at least at the surfaces ( 6   s   , 7   s ) of the rollers ( 6, 7 ) which make contact with the film ( 3 ), so that the film ( 3 ) can be inserted between said surfaces from the outside.

This application is a 371 of PCT/IB00/00284 dated Mar. 16, 2000.

TECHNICAL FIELD

The present invention relates to a device for loading film on machinesfor wrapping products.

BACKGROUND ART

Current machines for wrapping groups of products (of the automatic orsemi-automatic type) basically consist of a platform which supports thegroups of products on a pallet (the platform may be rotary or fixed) anda structure which supports the film feed means. This structure mayconsist of a simple vertical column, on which a unit equipped with theabove-mentioned film feed means (with rotary platform) slides in bothdirections, or may have horizontal arms or prongs which rotate about thegroup of products (usually with fixed platform).

The film feed means in turn consist of a film reel, rotatably mounted ona vertical shaft, which is attached to a plate which forms part of afeed means support carriage. In addition to the reel, there is aplurality of rollers, again with vertical axes attached to the plate,designed to allow the tensioned film to be guided and fed towards thegroup of products.

As well as these elements, in the current wrapping machines the use ofmotor-driven pre-stretching units for the wrapping film is increasinglycommon, especially when cold-stretch films are used. This pre-stretchingprocedure allows an increase in the film stabilising effect with aproportional reduction in the weight of the film on each group ofproducts wrapped.

In order to obtain correct stretching of the film fed, that is to say,without the film sliding around the rollers and, above all, without asignificant contraction or lateral reduction in the film web (whichcancels out the reduction in film weight), the use of at least one pairof motor-driven rollers, independent of one another, is necessary inorder to allow different peripheral speeds, with the two rollerspositioned very close to one another and a large angle for film windingaround the two rollers.

These operating conditions, together with the existing structure of thefeed means, mean that the film feed unit has a large number of rollerswhich are very close to one another on the drive carriage. Thisarchitecture, therefore, makes it difficult for the operator to load orinsert the film (when the reel ends or if the film breaks), since thespaces between rollers are very limited and there is also sometimes adanger that the operator's fingers may be crushed when manuallyinserting the end of the film.

In an attempt to overcome these disadvantages, the manufacturers ofthese machines designed a first solution consisting of a carriage whichsupports the reel and the guide and pre-stretching rollers in acantilever configuration, that is to say using only a support rod. Thisarchitecture partly solves the problem of loading the film in therollers (one end of the rollers is free), but requires precision sizingof the single support part and extremely stiff rollers (since there isonly one resting point) which considerably raises the cost of themachine, as well as complicating assembly. In addition, the transmissionand roller speed adjustment parts (variable speed motors and pulley/gearunits) are concentrated at one end of the rollers, making thelongitudinal dimension of the roller carriage very large and theconfiguration of the mechanisms which transmit motion to the rollerscomplex.

In a second solution, the support carriage was split into a fixed partand a mobile part, that is to say, a part which turns about a horizontalor vertical pivot axis. This solution allows the operator to load thefilm, after turning the mobile part, by threading the end of the filminto the free area of the fixed part.

However, the second solution also has disadvantages, due to theincreased size and weight of the carriage, necessary in order to splitit, with the consequent use of lifting parts suitable for this purpose,thus raising the cost of unit production. In this solution, thepre-stretching rollers must also be moved away from one another, and itis possible to reduce the winding angles, with the consequent risks thatthe quality of the pre-stretching operation may be lowered.

DISCLOSURE OF THE INVENTION

The aim of the present invention is, therefore, to overcome theabove-mentioned disadvantages by providing a device for loading filmwhich has an extremely compact structure, but which can be used at highspeed and allows the operator to rapidly insert the end of the filmbetween the pre-stretching rollers, whilst maintaining production levelssimilar to that of conventional machines.

The technical features of the present invention, in accordance with theabove-mentioned aims, are set out in the claims herein and theadvantages more clearly illustrated in the detailed description whichfollows, with reference to the accompanying drawings, which illustrate apreferred embodiment without limiting the scope of application, and inwhich:

FIG. 1 is a perspective view with some parts cut away to betterillustrate others, of the device for loading film made in accordancewith the present invention;

FIG. 2 is a top plan view of the device illustrated in FIG. 1;

FIG. 3 is a top plan view with some parts cut away to better illustrateothers, of the device illustrated in the previous figures.

With reference to the accompanying drawings and in particular FIG. 1,the device disclosed is used to load film, in particular but withoutlimiting the scope of its application, cold-stretch films, on machinesfor wrapping groups of products (of the known type and not illustrated).

The parts of these machines which form the subject matter of the presentinvention comprise a support frame 1 for the feed and preparation unit 2for the film 3 (that is to say, a film 3 cold pre-stretching unit) to bewrapped around the group of products.

The unit 2 comprises a carriage 4 which supports a reel 5 of film 3 withvertical axis Z in such a way that it can rotate, and at least one pairof rollers 6 and 7 which rotate about their axes Z1 and Z2, parallelwith the axis Z of the reel 5.

The two rollers 6 and 7 are designed to pre-stretch the film 3 and oneend of the rollers is attached to the carriage 4 by means of a platform8. The two rollers 6 and 7 (see also FIGS. 2 and 3) are positionedrelative to one another in such a way that they allow the passage of thefilm 3, with width L, along a feed path defined by part of thecorresponding outer circumference or contact surface 6 s and 7 s.

The carriage 4 is also equipped with a guard 9 which covers the end ofthe pair of rollers 6 and 7 opposite the end attached to the platform 8.This guard 9 covers each roller 6 and 7 in such a way that it defines acontinuous through-channel C passing at least between the contactsurfaces 6 s and 7 s of the rollers 6 and 7 for insertion of the film 3between the contact surfaces, from the outside.

In order to form the above-mentioned channel C, there are two holes 10and 11 passing through the guard 9 from the outside, at least at theopposite portions of the surfaces of the rollers 6 and 7 defining theabove-mentioned surfaces 6 s and 7 s for contact with the film 3 to bepre-stretched.

More specifically with reference to the construction details, the guard9 consists of at least two separate parts 9 a and 9 b, each supportingand covering a relative roller 6 and 7, defining another supportplatform for the rollers. In particular, the guard 9 defines an uppersupport platform for the carriage 4, securing the rollers 6 and 7 onboth sides.

In order to stiffen the guard 9 (so as to better secure the ends of therollers 6 and 7), each part 9 a and 9 b of the guard is individuallyattached to the other platform 8 by its vertical portions 12 and 13which cover part of each roller 6 and 7.

Obviously, these parts 12 and 13 extend at the side of areas of therollers 6 and 7 through which the film 3 does not pass.

As illustrated in FIGS. 1, 2 and 3, a third part 14 of the guard 9 isenvisaged, its structure similar to the other parts, which supports andcovers the upper end of the third feed roller 15 for the film 3, whichfeeds the latter towards the group of products to be wrapped, locatedclose to the pair of rollers 6 and 7.

Another particularly advantageous element of the device derives from thefact that each part 9 a, 9 b and 14 of the guard 9 has edges 17, 18 and19 which are rounded in the direction of the relative roller 6, 7 and 15and supported in such a way as to define a guide zone for the film 3 tobe inserted between said rollers. This feature allows rapid insertion ofthe film 3, preferably gathered in a bundle (not illustrated), from thetop of the carriage and without any risk to the operator.

Another feature of the present device relates to the pair of rollers 6and 7, which consists of motor-driven rollers (with mechanisms of theknown type, therefore not illustrated in detail).

The rotation of the motor-driven rollers is controlled by amicroprocessor unit 16 (which is part of the machine control unit, ofthe known type, therefore not illustrated).

In operation, this solution leaves one end of each roller free ofconnecting mechanisms (as in conventional models). Said end can be usedto connect the roller directly to the guard in a simple, compactfashion, instead of to the transmission.

The motor-driven rollers have frequency changers which, controlled bythe above-mentioned microprocessor, allow the speed of the rollers to beadjusted with continuous variations in the film 3 pre-stretching value,without using mechanical elements or having to substitute pinions/gears.

A device structured in this way, therefore, fulfills the preset aimsthanks to an extremely simple, compact structure and the use ofmotor-driven rollers which allow a reduction in the number of mechanicaldrive/speed change parts at the ends of the rollers. This particularfeature of the motor-driven rollers allows the guard at the top of therollers to be shaped so that it has a channel C for insertion of thefilm from the outside rapidly, safely and with easy manual operations.All of this is achieved while maintaining a stiffness of the structuresuitable for the work performed by the carriage and for filmpre-stretching requirements.

The carriage, therefore, has a reduced number of feed rollers, largeangles for winding around the pre-stretching rollers (see FIGS. 2 and 3)and a much reduced distance between the latter, to prevent reduction ofthe lateral strip of the film during stretching.

The present invention may be subject to numerous modifications andvariations, all encompassed by the design concept. Moreover, allcomponents may be substituted with technically equivalent parts.

What is claimed is:
 1. A device for loading film on machines forwrapping groups of products, the machines comprising a support frame fora feed and preparation unit for the film to be wrapped around the groupof products; said unit comprising at least one carriage, rotatablysupporting a reel of the film with a vertical axis, and at least onepair of rollers which rotate about their axes, parallel with the axis ofthe reel, one end of the rollers being attached to the carriage by meansof a platform, said pair of rollers being designed to allow the passageof the film along a feed path defined by part of the corresponding outercircumference or contact surface of each roller that contacts said film,said device also comprising a guard which covers the end of the pair ofrollers opposite that attached to the platform, said guard covering eachroller in such a way that at least at the contact surfaces of therollers it forms a continuous through-channel for insertion of the filminto the feed path from the outside, wherein said guard consists of atleast separate parts, each covering a respective roller, wherein eachpart of the guard is separately attached to the platform by verticalportions which at least partially cover the respective roller coveredthereby.
 2. The device according to claim 1, wherein the guard has holespassing through it from the outside at least at the portions of thesurfaces opposite the pair of rollers defining the surfaces which makecontact with the film.
 3. The device according to claim 1, wherein thepair of rollers consists of motor-driven rollers whose rotation iscontrolled by a microprocessor unit.
 4. The device according to claim 1,wherein the guard constitutes the upper support platform for thecarriage.
 5. A device for loading film on machines for wrapping groupsof products, the machines comprising a support frame for a feed andpreparation unit for the film to be wrapped around the group ofproducts; said unit comprising at least one carriage, rotatablysupporting a reel of the film with a vertical axis, and at least onepair of rollers which rotate about their axes, parallel with the axis ofthe reel, one end of the rollers being attached to the carriage by meansof a platform, said pair of rollers being designed to allow the passageof the film along a feed path defined by part of the corresponding outercircumference or contact surface of each roller that contacts said film,said device also comprising a guard which covers the end of the pair ofrollers opposite that attached to the platform, said guard covering eachroller in such a way that at least at the contact surfaces of therollers it forms a continuous through-channel for insertion of the filminto the feed path from the outside, wherein said guard consists of atleast separate parts, each covering a respective roller, said devicefurther comprising a third part of the guard, adapted to support andcover a third film feed roller close to the pair of rollers.
 6. Thedevice according to claim 5, wherein the guard constitutes an uppersupport platform for the carriage.
 7. A device for loading film onmachines for wrapping groups of products, the machines comprising asupport frame for a feed and preparation unit for the film to be wrappedaround the group of products; said unit comprising at least onecarriage, rotatably supporting a reel of the film with a vertical axis,and at least one pair of rollers which rotate about their axes, parallelwith the axis of the reel, one end of the rollers being attached to thecarriage by means of a platform, said pair of rollers being designed toallow the passage of the film along a feed path defined by part of thecorresponding outer circumference or contact surface of each roller thatcontacts said film, said device also comprising a guard which covers theend of the pair of rollers opposite that attached to the platform, saidguard covering each roller in such a way that at least at the contactsurfaces of the rollers it forms a continuous through-channel forinsertion of the film into the feed path from the outside, wherein saidguard consists of at least separate parts, each covering a respectiveroller, wherein each part of the guard has an outer edge which isrounded towards the roller, being supported in such a way as to form aguide zone for the film to be inserted between the rollers.
 8. Anapparatus comprising: a machine comprising a support frame for a feedand preparation unit for film to be wrapped around a group of products,said feed and preparation unit comprising: (i) at least one carriagerotatably supporting a reel of film that rotates about a reel axis; and,(ii) first and second rollers that rotate about respective axes that areeach parallel with the reel axis, a first end of each of the first andsecond rollers being attached to the carriage by means of a platform anda second end of each of the first and second rollers being spaced fromthe platform, said first and second rollers allowing passage of saidfilm therebetween along a feed path; a guard that covers the respectivesecond ends of the first and second rollers, said guard defining athrough-channel aligned with said feed path for insertion of filmthrough said guard between said first and second rollers into said feedpath in a direction transverse to said feed path, said guard comprisingat least a first part that covers said second end of said first rollerand a second part that covers said second end of said second roller. 9.The apparatus as set forth in claim 8, wherein said first part of saidguard rotatably supports said second end of said first roller and saidsecond part of said guard rotatably supports said second end of saidsecond roller.